18 



Fishery Bulletin 104(1) 



tainty. When uncertainty is considered, comparison to 

 even the lower end of estimates of prey removal are still 

 of note. For example, assuming that removal of juvenile 

 pollock is equal to the lower estimate, or 2.37x10'' kg, 

 the removal of pollock by humpback whales could still 

 equal 21,7% of the 2002 commercial pollock catch and 

 1.5% of 2002 spawning biomass. Thus, it follows that 

 if true consumption is actually closer to the upper esti- 

 mates, the impact of prey removal by humpback whales 

 would likely increase. 



The humpback whale represents only one of a myriad 

 of marine consumers within the Kodiak Island ecosys- 

 tem whose ecological role cannot be determined without 

 sophisticated multispecies models and an analysis of 

 ecosystem interactions. This study was designed to 

 provide essential baseline data and a model for estimat- 

 ing prey removal by foraging humpback whales. Our 

 results show that the potential for biomass removal due 

 to consumption by humpback whales is significant and 

 that the foraging strategies of these whales warrant 

 further investigation. Continued research efforts can 

 improve estimates of biomass removal by identifying 

 target prey, determining the degree of prey selectivity, 

 and assessing variable foraging efficiency. 



Acknowledgments 



The authors are grateful for the insight and guidance 

 provided by Janice M. Straley, Terry J. Quinn II, Bren- 

 dan P. Kelly, and Chris Gabriele. Field and labora- 

 tory assistance was provided by Lisa Baraff and Katie 

 Brenner. Financial support for this project was provided 

 by the Rasmuson Fisheries Research Center and NOAA 

 Grant no. NA16FX1270 to the University of Alaska Gulf 

 Apex Predator-Prey Project. All research was conducted 

 until provisions of NMFS Scientific Research Permit 

 473-1433. 



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